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JeffersonDeere

Potential CDI Issue 1987 350D?

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Hey Gang-

 

I have an awesome 1987 Rancher 350D. Great machine but am having the following issue:

 

The issue: It runs like a top, always starts up. However, at various times, it will randomly die and then not want to start, usually when I am right in the middle of chasing a cow or on the side of a highway in transit which is usually more of an inconvenience or embarrassment. I have noticed it is ALWAYS after it has been being run for at least 20 minutes. When I try to restart it, it will occasionally pop and cough but never gets close to running on its own. After a cool down (sometimes an hour, sometimes 12), it will fire back up like normal.

 

The ONLY other issue is that my oil temp light has started coming on when I first fire it up, usually when it is cold. Everything I have read seems to be leaning towards a CDI. Any insight from you all? I DO have a 1989 350D for parts as well but I understand the CDI for the 1987 model is unique to that model. Where do you recommend buying the CDI from? I WILL NOT buy a cheap aftermarket from Amazon and am willing to pay Shendig price! Thank you all in advance!

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Hi JeffersonDeere, welcome to ATVHonda!

 

Does your 87 Foreman lose spark when it stalls, or is the carb empty of fuel? If it is losing spark then the CDI may have a cold solder joint internally, or may have absorbed some moisture over the years. Look for tiny cracks in the potting/glue that is poured into the CDI case especially around the edges. You can put the CDI in an oven on low heat, approximately 230 degrees or so for about 30 minutes to boil any moisture out of it and sometimes the oven session fixes cold solder joints too, at least for a while... after you turn the oven off and allow the CDI to cool, seal up any cracks that may be in the potting with some sort of waterproof glue, use whatever ya have on hand.

 

As for the oil temp light coming on when the motor is first started, it sounds like the oil temp sensor resistance either have degraded and failed low, or the light blue wire coming out of the sensor may have a bare spot in the insulation that is touching/rubbing on the right side cover, grounding that wire out. Or, the fan control unit may be going bad. You can put the fan controller in the oven alongside the CDI if it is going bad. Might get lucky.

 

But first use a multimeter to measure the resistance through the two wires that go into the oil temp sensor to see if the sensor is bad. The resistance should measure between 9.5k ohms to 10.5k ohms at room temperature, or about 68 degrees F. If resistance measures much higher than 10.5k ohms then the sensor is not causing the oil temp light to come on. Look for a shorted wire or suspect the fan control unit. If resistance through the sensor is significantly lower than 9.5k ohms (less than 2k ohms) then the sensor could be the cause for the oil light coming on.

 

If the wire is grounding out causing the oil light to come on, or if the resistance through the oil sensor is very low, but the cooling fan does not run while the oil light is on then there is something wrong with the fan motor or the fan control unit.

 

@Gooberhas experience with baking CDIs and fan control units, hopefully he'll chime in with better advice than I can muster. Let us know what you learn so we can help ya, and learn from you.

 

EDIT: I will move this thread into the Utility > Electrical section after your next response

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Awesome, thanks a ton for the information.  I should have a chance to troubleshoot using the methods you wrote about.  I really appreciate the insight.  I will tackle and keep you posted on what I find! 

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Thanks @Retro and welcome @JeffersonDeere
I recommend you get some contact cleaner, permatex dielectric grease and a couple of plumbers flux brushes for cleaning your electrical connectors as you inspect each one.

 

your battery passes a load test? Best to rule out a weak battery first.

 

was your quad really hot when it shut down? you didn’t mention your fan coming on ever.

 

From the manual for check out the overheat system diagnostics:


When you switch on, you should get a steady neutral light and the oil light should come on momentarily and then go out. 


do you have a multimeter? Must be able to read Ohms, KiloOhms and Volts.
At any time (switched off), do a resistance check on your oil temp sensor before you start the quad. From the sensor center pin to the sensor body. At 77F the manual indicates the R values to be what Retro wrote. Higher than spec R values are common; the corrective action is to replace the sensor and continue troubleshooting.
 

While switched on. ground the blue wire to the foot peg. The fan should come on and the oil light should come on steady.

 

Good start here. There’s a hard copy TRX350 manual for sale on fleabay; going for $25-$30 right now

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Third step of ignition troubleshooting is to check for loose connector at CDI

 

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Question about G/W and Bl/W

is this at CDI?

 

D19E9AEE-D020-4D44-B11F-6B55F0A7BA24.jpeg

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Hey @Goober! Man, thank you so much for all the detailed info and steps to take.  I have dielectric grease, brushes, and contact cleaner on hand.  The battery is a brand new interstate, it does indeed pass a load test.  I dont feel as if the quad was really hot at any time this has happened however, I have never actually heard the fan come on so I will be checking this out as well per the details that you sent along.  I do indeed get the neutral light and a momentary oil temp light.  The oil temp light has been coming on intermittently IMMEDIATELY after starting which leads me to be suspect of a potential sensor or wiring issue as you mentioned.  I have her in my shop right now with the plastics still on.  I will be stripping that off and will shoot resistance this weekend and let you know what I find!  Thanks for the fleabay link, I will get that ordered right meow!  Thank you!!!!

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Hey Gang, sorry, it has been a while!  Got busy and the Honda moved down the project list....  BUT....  I have some good news to report.  I stripped the plastics off and ran it around like that for better troubleshooting purposes.  I have not had an oil temp issue since removing the plastics (though, I have the stock air intake and box removed so there is more air movement that previous).  I removed the connectors from the CDI, all looked good and had stock dielectric grease still in the plug (I am assuming it was stock grease).  I ran it around for a while and then it started its coughing and not wanting to start issue.  I reached up, tapped the CDI, and boom, she fired right up.  This happened about 6 times, EVERY time I tapped the CDI, she immediately fired again.  I think its safe to say that is the issue.  I would like to just buy another one, what vendor do you all recommend?  Thanks for all the help!

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Looks like it's $136 here, free shipping.

 

Just make sure on your year and model, as those old 350's all use a different CDI, and they don't interchange

 

Link is to a 1987 350D (look under wiring harness in the drop down, and then it's part number 3)

 

https://www.rockymountainatvmc.com/oem-schematic/8

 

There is also a 1987 350A and that one is different, so look at the old part and make sure the numbers match, or look at the sticker up front on the frame, which will say "350A" or "350D"

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I have the new CDI installed, ol' girl is running like a champ.  Thank you all so much for the insight and experience that you have with troubleshooting these awesome machines!

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count yer blessings !, most oem c.d.i.'s for these are discontinued today !. makes me wonder how you got yer hands on an oem c.d.i. ?..hmmmm..lol.

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Ha, @jeepwm69 hooked me up with a link to a parts supplier who had two available!  Hopefully, this one will last me for another 35 years.  Though, I may try the baking trick that @retro mentioned early on in this thread so as to have a viable backup.  Has anyone every disassembled to see about re-soldering some of the cold solder joints?  Just out of curiosity!

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1 hour ago, JeffersonDeere said:

Ha, @jeepwm69 hooked me up with a link to a parts supplier who had two available!  Hopefully, this one will last me for another 35 years.  Though, I may try the baking trick that @retro mentioned early on in this thread so as to have a viable backup.  Has anyone every disassembled to see about re-soldering some of the cold solder joints?  Just out of curiosity!

i have heard of stories of some taking them apart ?, but i have never tried it. the circuit board is incased in a solid rubber compound, and it will not be easy to get it all out, and out of the way from what i have seen.

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Looks like you got the last CDI Rocky Mountain had for the 87 350D.  They show unavailable for the 86-87 350A and the 88-up 350D, so you got lucky!

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3 minutes ago, jeepwm69 said:

Looks like you got the last CDI Rocky Mountain had for the 87 350D.  They show unavailable for the 86-87 350A and the 88-up 350D, so you got lucky!

yes he did !, i looked for one, for mine a couple days ago when i ran across this post, went to see if they had another ?, nope !. reason i went to look : i already knew honda discontinued them !..lol.

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Posted (edited)

Best bet is to inspect the CDI for breaks in the potting. Then bake connector-side-up at 200F for at least three hours. Let cool completely before you reseal any potting cracks. Then reinstall 

 

I tried to disassemble a bad CDI with zero luck. The circuit board is covered with electronics and tightly fitted into the plastic box, and encased in that potting compound. i tried to cut off the box with a cutting wheel—and cut the edge of the CB. in several places. Honestly i would have no idea how to fix one.

 

if you want to try—Lightly cut each of the 8 hard plastic corners and try to peel them off. this would expose all the potting. 

 

i saw a guy dissolve the potting in acetone. Yes it dissolves the potting, but also the jackets of the internal wiring and color coding of the components.

 

 

Edited by Goober
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@Goober, Oy vey.  Sounds like I will just be baking it as you suggested!  Based on how hard they are to find, I figure it might be handy to have the old one on hand (baked) as a backup in case its needed.  Thanks for all the help!

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Posted (edited)

Even faulty parts have value, if only for testing or to be scavenged for components. If you bake it and it is only temporarily revived, that’s good so you can use it for testing maybe a future foreman!

 

if you absolutely can’t get it to work and want to strip it open, hey at least share with us the process. I know you can cut the short corners with a dremel cutter. However, if i had a do-over, I would cut the case bottom corners steering on the large flat bottom instead of directly on the corner. The flat circuit board edges more closely align with the sides of the case, so if you cut along the short Side of the case you’re more likely to run into the circuit board.

Edited by Goober

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I have had very good luck "baking" both the fan controllers and CDI modules over the years

I have some folks tell me that are still working just fine 15 years after the fact 

I usually bake them at 450 for 7-8 minutes as most solder these days melts at 400-450 degrees 

I would say 8(ish) out of 10 times it fixes them   

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@Goober Haha, ah....You have pretty much convinced me NOT to attempt it!  I like the baking idea that you recommended along with @AKATV.  I can't tell you all how much I appreciate your help.  Thanks all!

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